diff --git a/ports/unix/main.c b/ports/unix/main.c
index 16f663de19..b065706ba6 100644
--- a/ports/unix/main.c
+++ b/ports/unix/main.c
@@ -69,6 +69,14 @@ long heap_size = 1024 * 1024 * (sizeof(mp_uint_t) / 4);
 #define MICROPY_GC_SPLIT_HEAP_N_HEAPS (1)
 #endif
 
+#if !MICROPY_PY_SYS_PATH
+#error "The unix port requires MICROPY_PY_SYS_PATH=1"
+#endif
+
+#if !MICROPY_PY_SYS_ARGV
+#error "The unix port requires MICROPY_PY_SYS_ARGV=1"
+#endif
+
 STATIC void stderr_print_strn(void *env, const char *str, size_t len) {
     (void)env;
     ssize_t ret;
@@ -538,44 +546,40 @@ MP_NOINLINE int main_(int argc, char **argv) {
     }
     #endif
 
-    char *home = getenv("HOME");
-    char *path = getenv("MICROPYPATH");
-    if (path == NULL) {
-        path = MICROPY_PY_SYS_PATH_DEFAULT;
-    }
-    size_t path_num = 1; // [0] is for current dir (or base dir of the script)
-    if (*path == PATHLIST_SEP_CHAR) {
-        path_num++;
-    }
-    for (char *p = path; p != NULL; p = strchr(p, PATHLIST_SEP_CHAR)) {
-        path_num++;
-        if (p != NULL) {
-            p++;
-        }
-    }
-    mp_obj_list_init(MP_OBJ_TO_PTR(mp_sys_path), path_num);
-    mp_obj_t *path_items;
-    mp_obj_list_get(mp_sys_path, &path_num, &path_items);
-    path_items[0] = MP_OBJ_NEW_QSTR(MP_QSTR_);
     {
-        char *p = path;
-        for (mp_uint_t i = 1; i < path_num; i++) {
-            char *p1 = strchr(p, PATHLIST_SEP_CHAR);
-            if (p1 == NULL) {
-                p1 = p + strlen(p);
+        // sys.path starts as [""]
+        mp_sys_path = mp_obj_new_list(0, NULL);
+        mp_obj_list_append(mp_sys_path, MP_OBJ_NEW_QSTR(MP_QSTR_));
+
+        // Add colon-separated entries from MICROPYPATH.
+        char *home = getenv("HOME");
+        char *path = getenv("MICROPYPATH");
+        if (path == NULL) {
+            path = MICROPY_PY_SYS_PATH_DEFAULT;
+        }
+        if (*path == PATHLIST_SEP_CHAR) {
+            // First entry is empty. We've already added an empty entry to sys.path, so skip it.
+            ++path;
+        }
+        bool path_remaining = *path;
+        while (path_remaining) {
+            char *path_entry_end = strchr(path, PATHLIST_SEP_CHAR);
+            if (path_entry_end == NULL) {
+                path_entry_end = path + strlen(path);
+                path_remaining = false;
             }
-            if (p[0] == '~' && p[1] == '/' && home != NULL) {
+            if (path[0] == '~' && path[1] == '/' && home != NULL) {
                 // Expand standalone ~ to $HOME
                 int home_l = strlen(home);
                 vstr_t vstr;
-                vstr_init(&vstr, home_l + (p1 - p - 1) + 1);
+                vstr_init(&vstr, home_l + (path_entry_end - path - 1) + 1);
                 vstr_add_strn(&vstr, home, home_l);
-                vstr_add_strn(&vstr, p + 1, p1 - p - 1);
-                path_items[i] = mp_obj_new_str_from_vstr(&vstr);
+                vstr_add_strn(&vstr, path + 1, path_entry_end - path - 1);
+                mp_obj_list_append(mp_sys_path, mp_obj_new_str_from_vstr(&vstr));
             } else {
-                path_items[i] = mp_obj_new_str_via_qstr(p, p1 - p);
+                mp_obj_list_append(mp_sys_path, mp_obj_new_str_via_qstr(path, path_entry_end - path));
             }
-            p = p1 + 1;
+            path = path_entry_end + 1;
         }
     }
 
@@ -710,7 +714,7 @@ MP_NOINLINE int main_(int argc, char **argv) {
 
             // Set base dir of the script as first entry in sys.path.
             char *p = strrchr(basedir, '/');
-            path_items[0] = mp_obj_new_str_via_qstr(basedir, p - basedir);
+            mp_obj_list_store(mp_sys_path, MP_OBJ_NEW_SMALL_INT(0), mp_obj_new_str_via_qstr(basedir, p - basedir));
             free(pathbuf);
 
             set_sys_argv(argv, argc, a);
diff --git a/ports/unix/mpconfigport.h b/ports/unix/mpconfigport.h
index 58aba9700b..c20aff1683 100644
--- a/ports/unix/mpconfigport.h
+++ b/ports/unix/mpconfigport.h
@@ -154,7 +154,7 @@ typedef long mp_off_t;
 // Ensure builtinimport.c works with -m.
 #define MICROPY_MODULE_OVERRIDE_MAIN_IMPORT (1)
 
-// Don't default sys.argv because we do that in main.
+// Don't default sys.argv and sys.path because we do that in main.
 #define MICROPY_PY_SYS_PATH_ARGV_DEFAULTS (0)
 
 // Enable sys.executable.
diff --git a/py/builtinimport.c b/py/builtinimport.c
index 8a125fc538..4fee04b8f3 100644
--- a/py/builtinimport.c
+++ b/py/builtinimport.c
@@ -118,7 +118,7 @@ STATIC mp_import_stat_t stat_top_level(qstr mod_name, vstr_t *dest) {
     #if MICROPY_PY_SYS
     size_t path_num;
     mp_obj_t *path_items;
-    mp_obj_list_get(mp_sys_path, &path_num, &path_items);
+    mp_obj_get_array(mp_sys_path, &path_num, &path_items);
 
     // go through each sys.path entry, trying to import "<entry>/<mod_name>".
     for (size_t i = 0; i < path_num; i++) {
@@ -365,7 +365,7 @@ STATIC mp_obj_t process_import_at_level(qstr full_mod_name, qstr level_mod_name,
     // which may have come from the filesystem.
     size_t path_num;
     mp_obj_t *path_items;
-    mp_obj_list_get(mp_sys_path, &path_num, &path_items);
+    mp_obj_get_array(mp_sys_path, &path_num, &path_items);
     if (path_num)
     #endif
     {
diff --git a/py/modsys.c b/py/modsys.c
index 72817ce009..9b3a2bc163 100644
--- a/py/modsys.c
+++ b/py/modsys.c
@@ -195,6 +195,9 @@ STATIC mp_obj_t mp_sys_settrace(mp_obj_t obj) {
 MP_DEFINE_CONST_FUN_OBJ_1(mp_sys_settrace_obj, mp_sys_settrace);
 #endif // MICROPY_PY_SYS_SETTRACE
 
+#if MICROPY_PY_SYS_PATH && !MICROPY_PY_SYS_ATTR_DELEGATION
+#error "MICROPY_PY_SYS_PATH requires MICROPY_PY_SYS_ATTR_DELEGATION"
+#endif
 
 #if MICROPY_PY_SYS_PS1_PS2 && !MICROPY_PY_SYS_ATTR_DELEGATION
 #error "MICROPY_PY_SYS_PS1_PS2 requires MICROPY_PY_SYS_ATTR_DELEGATION"
@@ -211,6 +214,11 @@ MP_DEFINE_CONST_FUN_OBJ_1(mp_sys_settrace_obj, mp_sys_settrace);
 #if MICROPY_PY_SYS_ATTR_DELEGATION
 // Must be kept in sync with the enum at the top of mpstate.h.
 STATIC const uint16_t sys_mutable_keys[] = {
+    #if MICROPY_PY_SYS_PATH
+    // Code should access this (as an mp_obj_t) for use with e.g.
+    // mp_obj_list_append by using the `mp_sys_path` macro defined in runtime.h.
+    MP_QSTR_path,
+    #endif
     #if MICROPY_PY_SYS_PS1_PS2
     MP_QSTR_ps1,
     MP_QSTR_ps2,
@@ -231,8 +239,9 @@ void mp_module_sys_attr(mp_obj_t self_in, qstr attr, mp_obj_t *dest) {
 STATIC const mp_rom_map_elem_t mp_module_sys_globals_table[] = {
     { MP_ROM_QSTR(MP_QSTR___name__), MP_ROM_QSTR(MP_QSTR_sys) },
 
-    { MP_ROM_QSTR(MP_QSTR_path), MP_ROM_PTR(&MP_STATE_VM(mp_sys_path_obj)) },
+    #if MICROPY_PY_SYS_ARGV
     { MP_ROM_QSTR(MP_QSTR_argv), MP_ROM_PTR(&MP_STATE_VM(mp_sys_argv_obj)) },
+    #endif
     { MP_ROM_QSTR(MP_QSTR_version), MP_ROM_PTR(&mp_sys_version_obj) },
     { MP_ROM_QSTR(MP_QSTR_version_info), MP_ROM_PTR(&mp_sys_version_info_obj) },
     { MP_ROM_QSTR(MP_QSTR_implementation), MP_ROM_PTR(&mp_sys_implementation_obj) },
@@ -308,10 +317,11 @@ const mp_obj_module_t mp_module_sys = {
 // available.
 MP_REGISTER_MODULE(MP_QSTR_sys, mp_module_sys);
 
-// If MICROPY_PY_SYS_PATH_ARGV_DEFAULTS is not enabled then these two lists
-// must be initialised after the call to mp_init.
-MP_REGISTER_ROOT_POINTER(mp_obj_list_t mp_sys_path_obj);
+#if MICROPY_PY_SYS_ARGV
+// Code should access this (as an mp_obj_t) for use with e.g.
+// mp_obj_list_append by using the `mp_sys_argv` macro defined in runtime.h.
 MP_REGISTER_ROOT_POINTER(mp_obj_list_t mp_sys_argv_obj);
+#endif
 
 #if MICROPY_PY_SYS_EXC_INFO
 // current exception being handled, for sys.exc_info()
diff --git a/py/mpconfig.h b/py/mpconfig.h
index b6f8838662..eb23c5965c 100644
--- a/py/mpconfig.h
+++ b/py/mpconfig.h
@@ -1421,6 +1421,23 @@ typedef double mp_float_t;
 #define MICROPY_PY_SYS_ATEXIT (0)
 #endif
 
+// Whether to provide the "sys.path" attribute (which forces module delegation
+// and mutable sys attributes to be enabled).
+// If MICROPY_PY_SYS_PATH_ARGV_DEFAULTS is enabled, this is initialised in
+// mp_init to an empty list. Otherwise the port must initialise it using
+// `mp_sys_path = mp_obj_new_list(...)`.
+#ifndef MICROPY_PY_SYS_PATH
+#define MICROPY_PY_SYS_PATH (1)
+#endif
+
+// Whether to provide the "sys.argv" attribute.
+// If MICROPY_PY_SYS_PATH_ARGV_DEFAULTS is enabled, this is initialised in
+// mp_init to an empty list. Otherwise the port must initialise it using
+// `mp_obj_list_init(MP_OBJ_TO_PTR(mp_sys_argv), ...);`
+#ifndef MICROPY_PY_SYS_ARGV
+#define MICROPY_PY_SYS_ARGV (1)
+#endif
+
 // Whether to provide sys.{ps1,ps2} mutable attributes, to control REPL prompts
 #ifndef MICROPY_PY_SYS_PS1_PS2
 #define MICROPY_PY_SYS_PS1_PS2 (MICROPY_CONFIG_ROM_LEVEL_AT_LEAST_EXTRA_FEATURES)
@@ -1455,7 +1472,7 @@ typedef double mp_float_t;
 // Whether the sys module supports attribute delegation
 // This is enabled automatically when needed by other features
 #ifndef MICROPY_PY_SYS_ATTR_DELEGATION
-#define MICROPY_PY_SYS_ATTR_DELEGATION (MICROPY_PY_SYS_PS1_PS2 || MICROPY_PY_SYS_TRACEBACKLIMIT)
+#define MICROPY_PY_SYS_ATTR_DELEGATION (MICROPY_PY_SYS_PATH || MICROPY_PY_SYS_PS1_PS2 || MICROPY_PY_SYS_TRACEBACKLIMIT)
 #endif
 
 // Whether to provide "errno" module
diff --git a/py/mpstate.h b/py/mpstate.h
index 3786131de6..080dc1380b 100644
--- a/py/mpstate.h
+++ b/py/mpstate.h
@@ -43,6 +43,9 @@
 #if MICROPY_PY_SYS_ATTR_DELEGATION
 // Must be kept in sync with sys_mutable_keys in modsys.c.
 enum {
+    #if MICROPY_PY_SYS_PATH
+    MP_SYS_MUTABLE_PATH,
+    #endif
     #if MICROPY_PY_SYS_PS1_PS2
     MP_SYS_MUTABLE_PS1,
     MP_SYS_MUTABLE_PS2,
diff --git a/py/runtime.c b/py/runtime.c
index 2326dfb3ca..f5d219728f 100644
--- a/py/runtime.c
+++ b/py/runtime.c
@@ -136,13 +136,17 @@ void mp_init(void) {
     #endif
 
     #if MICROPY_PY_SYS_PATH_ARGV_DEFAULTS
-    mp_obj_list_init(MP_OBJ_TO_PTR(mp_sys_path), 0);
+    #if MICROPY_PY_SYS_PATH
+    mp_sys_path = mp_obj_new_list(0, NULL);
     mp_obj_list_append(mp_sys_path, MP_OBJ_NEW_QSTR(MP_QSTR_)); // current dir (or base dir of the script)
     #if MICROPY_MODULE_FROZEN
     mp_obj_list_append(mp_sys_path, MP_OBJ_NEW_QSTR(MP_QSTR__dot_frozen));
     #endif
+    #endif
+    #if MICROPY_PY_SYS_ARGV
     mp_obj_list_init(MP_OBJ_TO_PTR(mp_sys_argv), 0);
     #endif
+    #endif // MICROPY_PY_SYS_PATH_ARGV_DEFAULTS
 
     #if MICROPY_PY_SYS_ATEXIT
     MP_STATE_VM(sys_exitfunc) = mp_const_none;
diff --git a/py/runtime.h b/py/runtime.h
index 78194973d6..c033c77b40 100644
--- a/py/runtime.h
+++ b/py/runtime.h
@@ -227,8 +227,13 @@ int mp_native_type_from_qstr(qstr qst);
 mp_uint_t mp_native_from_obj(mp_obj_t obj, mp_uint_t type);
 mp_obj_t mp_native_to_obj(mp_uint_t val, mp_uint_t type);
 
-#define mp_sys_path (MP_OBJ_FROM_PTR(&MP_STATE_VM(mp_sys_path_obj)))
+#if MICROPY_PY_SYS_PATH
+#define mp_sys_path (MP_STATE_VM(sys_mutable[MP_SYS_MUTABLE_PATH]))
+#endif
+
+#if MICROPY_PY_SYS_ARGV
 #define mp_sys_argv (MP_OBJ_FROM_PTR(&MP_STATE_VM(mp_sys_argv_obj)))
+#endif
 
 #if MICROPY_WARNINGS
 #ifndef mp_warning
diff --git a/shared/upytesthelper/upytesthelper.c b/shared/upytesthelper/upytesthelper.c
index 12fa8276b0..ba20037f7a 100644
--- a/shared/upytesthelper/upytesthelper.c
+++ b/shared/upytesthelper/upytesthelper.c
@@ -31,6 +31,14 @@
 #include "py/compile.h"
 #include "upytesthelper.h"
 
+#if !MICROPY_PY_SYS_PATH
+#error "upytesthelper requires MICROPY_PY_SYS_PATH=1"
+#endif
+
+#if !MICROPY_PY_SYS_ARGV
+#error "upytesthelper requires MICROPY_PY_SYS_ARGV=1"
+#endif
+
 static const char *test_exp_output;
 static int test_exp_output_len, test_rem_output_len;
 static int test_failed;
@@ -93,7 +101,7 @@ void upytest_execute_test(const char *src) {
     // reinitialized before running each.
     gc_init(heap_start, heap_end);
     mp_init();
-    mp_obj_list_init(mp_sys_path, 0);
+    mp_sys_path = mp_obj_new_list(0, NULL);
     #if MICROPY_MODULE_FROZEN
     mp_obj_list_append(mp_sys_path, MP_OBJ_NEW_QSTR(MP_QSTR__dot_frozen));
     #endif